This invention relates to an optical deflector which can change the index of refraction of a photo-conductive material transparent relative to light to thereby deflect a course of light.
Recently, with the development of photo-electronic appliances such as photo-video disc and photo-communication system, the development of an optical deflector which can freely deflect the course of light has been an urgent subject, and optical deflectors which makes use of various effects have been proposed.
Optical deflectors heretofore proposed make use of an electric field (electro-optical effect), magnetic field (magnetic optical effect) or surface accoustic wave (acoustic optical effect). For example, in the optical deflector making use of the electro-optical effect, a thin film waveguide is formed on the substrate (such as LiNbO.sub.3) and an electric field is applied to the thin film waveguide. Then, distribution of refractive index of the thin film waveguide varies with the applied electric field to deflect the projected lightbeam.
However, since in the optical deflector heretofore proposed, the deflection angle depends upon the polarized surface of an incident light beam, it is difficult to obtain a predetermined deflection angle unless means for arranging in advance the polarized surface of the incident light beam is provided.
In addition, if the film thickness of the optical waveguide is made greater, the effect is different in a direction of depth, and therefore, it is difficult to form a thick film waveguide.